Download - Army Aviation Digest - Jan 1988

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PROFESSIONAL BULLETIN

EllisD.8 Decolmores,sic)n S i c k n e ~ s s - - H l e c k I Don't Even

Scuba M.D. and MAJRobert A. Mitchell

12 Wire 9 t 9 f ~ t I C l l n - - H I I ~ t t l f V and Mr. AlfredKleider

17 PEARL'S20 DES ~ A r ' n r t21 Editor Retires

Consolidation ofRe'Qullatlons. Mr. James P. Wall22 Aviation Personnel Notes:

PersonnelAviation Personnel Plan

24 A Total fo r Battle, Mr. Ron Brunelle37

4044

and Mr. A. 1\ /11 ' \ ,1 ' \ ' - ' ' ' " ,

Jr.Aviation " " ' 'MG"U,


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WILDCARDONTHE

BATTLEFIELDLieutenant Colonel William R. Clontz

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JANUARY 1988

. ~ a ",i - 1 ~ 1 ~ ~i 4 < f ~ J - -i Army Aviation has the speed, mobility and~ flexibility not only to influence the battlefield butIJl~ at times to control it, as has been reported in earlierarticles in the Aviation Digest. A recent National Traininga. Center exercise by elements of the 24th Infantry Division(Mechanized) confirmed this precept and validated how toassure success on the battlefield.

THE OPPOSING FORCES(OPFOR) commander walked awayfrom his command track into the coolnight air, his head full of thoughtsabout the coming battle. He hadfought enough actions like this one inrecent months and was confident tha the had prepared as fully as possiblefor tomorrow's action. Still ... histime was different; the Blue Forceswere using their aviation in disturbingand unpredictable ways. The Armyhelicopters were proving increasinglyeffective in recent days, seldom striking the same way twice. Losses weremounting at an unacceptable rate,.without a corresponding loss of helicopters. The aviation element had"broken the code" of the battlefieldand theOPFOR was paying the price.

The 24th Combat Aviation Battalion went to the National TrainingCenter (NTC) with the goal of settinga battlefield tempo as describedabove. We found that the applicationof well-established principles andtechniques, modified to take advantage of ever-changing opportunities,yielded repeated success. Our experience at NTC demonstrated clearlytha t simple analysis of problems and

opportunities before committing assets kept the enemy off balance andled to victory. The following is a review of major lessons learned by thesoldiers of the Victory Division.

Measure the Kill Probability.Commitment of assets should bepredicated on a reasonable chance ofinflicting significantly more damageon the enemy than he can expect to inflict on you. Avia tion assets are incredibly effective but they also are incredibly expensive and are fielded inlow density; use them accordingly.An important example is provided byemployment of attack aviation assetsagainst dug-in hard targets, especiallyat short ranges. This is a no return operation, sure to result in high aircraftloss rates, as the risk to thin skinnedaircraft is high while the probabili tyof a tank kill is near zero. A usefulvariation is to move in behind the enemy positions and engage as he movesof f the position or makes a lateralmovement. A more conventionalhead-on attack will prove too expensive. Find the rear attack opportunityor wait for another battle. This is arelatively high risk option that demands the right conditions to suc-

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WILDCARD ON THE BATTLEFIELD

ceed. Excessive loitering or choosingthe wrong position can be fatal. Pursue this option with the greatest ofcare and on rare occasions.Night Vision Goggles (NVG)Work for Attack Operations. Shooting with goggles is difficult at best,particularly with TOW missiles, andis generally no t a best use of re-sources. However, the goggles are absolutely invaluable in executing highspeed, low level night movementacross the forward line of own troops(FLOT), assuring strike elements willbe in position for first light attacks.Our NVG teams were consistentlysuccessful in breaking the rhythm ofenemy attacks and in disrupting his

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formations from the rear. They werealso of great value before first lightfor spot reports and to call in artilleryat maximum ranges.Enter At the Weak Points and Go

For Soft Targets. Good templatingtells you where the enemy boundariesare. Crossing the FLOT at thesepoints lowers the risk of taking fire,and even of discovery. Small groupsof aircraft or individual aircraft moving under cover of darkness at highspeed and blacked out, using multipleand varied routes, are difficult targetsfor OPFOR gunners. We receivedfeedback from the OPFOR that theycould sometimes hear these aircraftbut could no t see them, nor track

them with any precision.Once through the FLOT, tacticalsituation permitting, go deep to strikepreviously identified and templatedsoft targets such as rear services unitsand communications assets; thenproceed forward to command andcontrol targets, artillery positions,and helicopter laager sites, engagingforward hard targets last. This technique maximizes the range and typesof damage inflicted. Rolling up targets from the rear offers advantagesin terms of target numbers versusrisks. This represents something of areversal of the normal procedure thatcalls for attacking hard targets first. Itshould not be construed as a reversalof priorities, however; it is simplycoming at these same targets fromnew directions and engaging othervaluable assets as the attack movesforward. I f we were to concentrateonly on the hard targets and only in adogmatic order, we would deny thevalue of destroying support echelons.A greater number of targets are available with a lessened concentration ofair defense artillery attuned to the helicopter threat. It also makes counterattack more difficult as the aircraftdo not remain in anyone area long.

An attack of this sort, a running attack in a zone as opposed to a pinpoint attack on specified targets, willnot completely destroy many targetsbut will render many targets combatineffective and confuse the enemy asto just how many aircraft are attacking him from how many positions.This concept should be employedwhen mission, enemy, troops, terrainand time (METT-T) and intelligencesupport its use. Vary this attack concept with more conventional ap-proaches as necessary to get to the targets and to complicate OPFORsecurity planning.

Plan On Poor Communications.You are not likely to be disappointed!Communications between attack aviation and ground elements are oftentenuous at best, especially back to brigade or division. Rough terrain suchas is found at NTC frequently eliminates communication entirely for

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brief periods. This may require additional aircraft, dismounted scouts orrelays on the battlefield to pass information and to assure that artillery,Air Force and other assets ar esmoothly integrated into the battle.Where feasible, dedicated aircraft forairborne forward air control and firesupport officer personnel pay dividends in terms of syncronization andthe ability to place key players at oneplace for face to face coordination.Aviation elements en route back tothe forward arming and refuelingpoint (FARP) or rear areas must routinely take advantage of reduced distances to talk to higher headquarters,provide updates and pass on requests.It's an informal and impromptu system that is essential to keep everyoneabreast of the situation. Just remember to keep such transmissions short,perhaps by use of brevity codes, andto terminate them early to avoid electronic warfare targeting 0 f the FARPor command posts.

Know Who You Work For andWho Your Friends Are. Attack assetsare best employed at division level,

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orchestrated by the aviation brigade,although METT-T may dictate otherwise for specific situations. Assetsmay be OPCON (operational control) at times to ground maneuver brigade level on a mission basis, but thisis the lowest levelat which aviation assets should be allocated. Operationbelow this level negates the speed,mobility and surprise that are inherent in aviation. Employment withoutthese elements only serves to diffusecombat power rather than concentrate it; what could be an opportunitybecomes a problem; a risk.This does not negate the requirement to talk to battalion or companylevel forces on the ground, exactly theopposite. Forward ground elementsusually have the most current information as to specific targets and dangers in their zone. Ground and airplans, as well as execution, mustdovetail or they are wasted, even mutually defeating. Supporting and direct fires also must be coordinated toachieve th e synergistic effect re-quired. The brigade headquarters isthe ideal place to effect most of this

coordination initially, followed bydirect conversation on FM (frequencymodulated) during the battle.Keep a Clear Channel Open to theArtillery. Do this at the lowest possible level. The combination of aerialscout and artillery is powerful bu tonly if it functions quickly. Distance,terrain and communications availability will determine the best option.One possible solution is to have the attack aviation commander workthrough the fire support element netof the closest ground battalion taskforce, assuming the commander doesnot have an airborne fire support officer. Use of a digital message devicein the aircraft to tie into the artillerynet is an obvious and excellent solution when available. Keep other options open; this is not a link you canafford to lose. It often means the difference between surviving a battleand winning it. The best option is to atleast secure priority of fires duringcritical phases of the battle. Wherepossible, request fire support via adedicated battery (or more) and discreet frequencies during critical peri-

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D Keep the enemy offbalance.

ods. These dedicated assets are essential when fighting well forward of theFLOT.Keep the Enemy Off Balance. Successful techniques should be repeatedbut not excessively to the point of predictability. As an example, we wentfrom deep attacks with TOWs on agiven day, followed by massed fires5,000 meters to the rear with rocketsthe following day. Aviation practically owns the mobility aspect of thebattlefield. Failure to use this advantage is unacceptable. Make the enemyspend inordinate amounts of ime, resources and energy trying to counteryour moves. In this way, you defeathim and make it easier for the othermembers of the combined arms teamto do their j ob. The proper use ofmo-

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bility is directly connected to the ability to mass fires. Don't automaticallyuse the one-third rule for continuouscoverage. There will be times when itpays to let coverage deplete, evenlapse, to ensure sufficient mass offires at the critical opportunity .Jump FARPs Are Critical. Wefound it necessary to move FARPsoften; various techniques worked.We relied on slingloading of forwardarea refueling equipment systemsandblivets, with crews carried in the sameUH-60s. Securing the equipment toAir Force pallets facilitated the movement process and reduced setuptimes. Maintaining a spot decontamination capability is essential at everyFARP. The FARP also must have anindependent means of communica-

tions and some means of ground andair defense. Insist on equipping yourFARPs with Stinger antiaircraft missiles. In mechanized warfare, theFARP is subject to being overrunwith great speed. This danger requires an integrated mobility andcommunication capability, as well asa plan to relocate at a given time; i.e.,when enemy elements reach positionX the FARP will displace. This assures the safety of the FARP even ifcommunications are disrupted or ifkey leaders are out of touch. Obviously, fielding of the heavy expandedmobility tactical truck will radicallyalter the possibilities for FARP operations and movement.Avoid Map Clutter. Maps are often obscured with massive amountsof data. All of it essential to everycrew. Consider splitting up what isposted between crewmembers in thesame aircraft, but do keep completegraphics in the cockpit. Cobra leadmay be called upon to fulfill the dutiesof scout 1, etc. Therefore, no shortcu t on graphics is acceptable. Justknowing your piece of the action isnot enough; crews must have an understanding of the larger concept ofthe battle.

Weigh the Tradeoff s In Basing Locations. A good case can be made forplacing your assets as far forward aspossible, thus reducing deploymenttimes and facilitating coordination.However, placing these assets towardthe rear, even in the division suppor tarea, greatly facilitates crew endurance (usually involving fewer displacements) and better aircraft maintenance, as aircraft aviation unitmaintenance and aviation intermediate maintenance are closer together.The subject of crew endurance is onethat deserves emphasis. It is a leadership and a management issue thatcannot be casually waived withoutunacceptable costs. Assuring crewsget adequate rest in terms of quantityand quality is a command responsibility. Recognize the variables such asintensity of he battle and physiology,and enforce procedures accordingly.Aviation commanders have to lead

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the way on this issue. The risks of en-emy attack and targeting are presentin both options, though with differ-ent specific types of threat. A judi-cious mix might consist of rearwardbasing with a jump tactical opera-tions center, FARPs and flight ele-ments ready to displace on a missionbasis at any time. Prepositioning offuel facilitates use of this option. Thecentral issue to be addressed is thetradeoffs in security versus respon-siveness, in quality maintenance andrest versus reaction times. Battlefieldconditions and aviation mobilitywillgive you several possible equations.Don't assume only one answer is al-ways correct; be prepared to executedifferent options at all times. I f noth-ing else, this flexible approach makestemplating more difficult for theOPFOR.The above discussion covers only afew of the issues that duty at NTCraised for the 24th Combat AviationBattalion. The center provides an un-paralleled opportunity for trainingthat should be seized. The NTC is es-sentially geared to combat at the

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D Weigh the tradeoffs inbasing locations.

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ground battalion task force level andcurrently limits aviation play sub-stantially. Nevertheless it's greattraining. As aviation continues to in-crease its impact on the battlefield,NTC rules and procedures will ex-pand to more realistically employourresources; the cadre at NTC is hard at

work making this a reality. Whateverexternal limitations apply, aviationleaders should remember the real lim-iting factor is our own imaginationand daring. Audacity and innova-tion teamed up with good judgmentand professional skills will win thebattle. FIRST TO FLYl ~

ABOUT THE AUTHORAt the time this article was written, LTC William R.

Clontz was the commander of the 24th Combat AviationBattalion, 24th Infantry Division (Mechanized) at HunterArmy Airfield, GA. He now commands the newlyactivated 24th Attack Helicopter Battalion of the AviationBrigade, 24th Infantry Division (Mechanized). He is aSenior Aviator, a Senior Parachuti st and is SpecialForces qualified. He is a graduate of the Infantry OfficerAdvanced Course, Special Forces Officer Course,Command and General Staff College, Foreign AreaOfficer Course, and the French Ecole Superieur deGuerre Interarmee. He has a master's degree in publicadministration and is rated in AH-1, UH-1, UH-60 andOH-58 aircraft.

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rAT STATEMENT summa-rizes the average Army Aviator's at-titude toward decompression sick-ness. Unless he or she is a scuba diver,the last time an Army aviator thoughtabout decompress ion sickness wasright after altitude chamber exposureduring the first week of flight school.However, altitude induced decom-pression sickness remains a seriousthreat to aviators who fly above18,000 feet, mean sea level (MSL),and aviators who scuba dive. Just be-cause you are not a member of eithergroup, now is not the time to skip onto another article. Besides, how manyofyou have totally givenup on receiv-ing a fixed wing transition, andyou're never too old to learn to scubadive.

Altitude induced decompressionsickness is no different from decom-pression sickness induced by scubadiving. Whenever there is a sufficientreduction in atmospheric pressure,bubbles of nitrogen will evolve frombody tissue. This is similar to openinga soft drink bottle that has beenshaken. These bubbles may then set-tle in the joints and tendons causingthe bends, or maybe in the central ner-vous system causing a central nervoussystem disorder. Either one of thesedisorders could have a serious effecton an aviator's career. Even simpleortype I bends will require the aviator tobe grounded for a short period of

time. A case of ype II decompressionsickness (central nervous system in-volvement) requires an aviator to begrounded until an aeromedical sum-mary is prepared and reviewed by theAeromedical Consultants AdvisoryPanel at the U.S. Army AeromedicalActivity, Ft. Rucker, AL. We in theArmy are more fortunate than avia-tors in the U.S. Air Force who are per-manently grounded for type II de-compression sickness.The maximum altitude belowwhich not enough bubbles will evolveout of solution to cause decompres-sion sickness is unknown. For mostof the 20th century it was thought tobe 18,000 feet MSL. This altitude isbased on the theory proposed byCommander J. S. Haldane in his re-port to the Lords Commissioner ofthe Admiraltyon deep diving in 1907.Haldane postulated that a drop ofabout one-half of the original gaspressure would be safe whatever itsvalue; i.e., 132 feet deep to 66 feetdeep; 66 feet deep to sea level; sealevel to 18,000 feet mean sea level. Itwas Haldane's 2:1 Rule on which allearly diving tables and the 18,000 feetMSL theory were based. Currentstudies by National Aeronautics andSpace Administration and BrooksAFB, TX, have proven that Haldane's 2: 1 Rule is not conservativeenough. These studies have shownthat the true critical ratio is about



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1.54: 1 or about 12,000 feet MSL.To better protect the Army aviatorflying high altitude unpressurized

missions, Army Regulation 95-1,"General Provisions and Flight Regulations," was changed. Effective 22August 1985, the altitude at which 30minutes of prebreathing 100 percentoxygen at ground level is required wasreduced from 20,000 feet MSL to18,000 feet MSL. The current editionof AR 95-1, dated 1 October 1987,continues to reflect this change.When the change was being staffedno one could determine a physiological reason why 20,000 feet MSL hadever been established. However,there is numerous evidence supporting 18,000 feet MSL.Most of the data and studies supporting the reduction to 18,000 feetMSL comes from the U.S. Air Force.This is a paradox since the U.S. AirForce does no t have an Air Forcewide regulation requiring prebreathing prior to unpressurized flight up to25,000 feet MSL. However, there arenumerous operational procedures requiring prebreathing prior to exceeding 18,000 feet MSL.

The authors could find only twodocumented cases of altitude induceddecompression sickness in Army aircraft. This is not because the Armyexperiences so few cases of altitudeinduced decompression sickness. Theproblem is twofold. First, the Army

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Major John McNamara, M.D.Major Robert A. Mitchell

did not centrally collect data on decompression sickness. Second, mostcases of decompression sickness aresimple pains only bends and are notreported. Some aviators who experience a nonspecific joint pain after amission tend to ascribe it to age, exercise or other muscle strain rather thanconsult the flight surgeon. It's usuallya case of , "M y shoulder always hurtsafter I've flown at 23,000 feet MSLfor 4 hours, but the pain always goesaway after two aspirins and a coupleof beers. " The Army does, however,have substantial data collected in itsaltitude chamber that support the reduction to 18,000 feet MSL.Most aviators feel that altitude induced decompression sickness is anAir Force problem because they fly somuch higher than the Army. TheU.S. Air Force had 90 decompressionsickness mishaps in the 10 years, 1975to 1985; 76 or 85 percent were at altitudes below 25,000 feet MSL. Of special note are the 15 mishaps (17 percent) at altitudes below 18,000 feetMSL. Curren t studies at the U.S. AirForce School of Aerospace Medicineat Brooks AFB, TX, by Gene Dixon,have demonstrated reproduciblebends in test subjects as low as 16,500feet MSL. These altitudes are wellwithin the operational flight levels ofmany Army missions.It is important that we dispel themyth that bends are not that serious,

an d they are just the cost of doingbusiness in high altitude unpressurized flight. As already mentioned,they can have a direct effect on anaviator's flight status . Even a temporary loss of such a valuable asset as anaviator cannot be tolerated withtoday's manpower constraints. Moreimportant, simple type I bends,which are not career threatening, canprogress to more serious medicalproblems. Temporary serious loss ofvision has been documented as low as20,000 feet MSL and death in twocases at 20,000 and 22,000 feet MSL.

Who is at greatest risk in theArmy Aviation community?There are two groups of Army aviators that are at greatest risk. First,are those crewmembers who repeatedly fly high alti tude unpressurizedmissions. Second, are those crewmembers who scuba dive as a sport.The two operational cases of altitudeinduced decompression sickness reported in the Army were pilots of anOV-l and a U-21 flown at 19,000 and21,000 feet MSL respectively. Additionally, aviators need to be observantofthe "pseudo" aviation group,HAHO and HALO parachute jump-ers, who are at equal if not greater riskof decompression sickness.

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A study of altitude chamber operations at the U.S. Army School ofAviation Medicine revealed some important facts that directly relate to operational missions. This studyshowed that technicians who wereroutinely exposed to altitude had a100fold greater risk ofdecompressionsickness than students . The most active technician made only 41 chamberflights per year, which is considerablyless than the number of flights peryear made by most pilots in someArmy units. The median age of thetechnicians fell into the 31 to 35 yearsold bracket as opposed to the 21 to 25years old bracket for students. Theaverage age of the crewmembers whofly the high altitude missions is considerably higher than that of the average aviation unit. Age is aprovenfac-tor contributing to decompressionsickness.

Scuba diving less than 24 hoursprior to flight is a major contributingfactor to decompression sickness.When people scuba dive, theysupersaturate their body with nitrogen while breathing compressed air atdepths greater than one atmosphere.When they come to the surface nitrogen bubbles will evolve out of solution. I f they obeyed the U.S. Navydiving tables, they have less than a 5-percent chance of developing decompression sickness. However, if theyshould fly within the next 24 hourswith the excess nitrogen in their bodythey are at much greater riskof developing decompression sickness. Thereare numerous documented cases ofdecompression sickness at altitudesless than 8,000 feet MSL in crewmembers who had been scuba divingin the preceding 24 hours. A major

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cause of crewmembers' flying afterless than 24 hours is that most sportscuba diving courses teach a period ofonly 12 hours for the removal of residual nitrogen. This time period is indirect contradiction to AR 40-8,"TemporaryFlying Restrictions Dueto Exogenous Factors."How to PreventDecompression Sickness

First, we must educate the unitcommanders. The U.S. Army did notstart altitude chamber training until1971. All Army aviators were no ttrained in the altitude chamber until1975. There are senior Army aviatorswho have never had altitude physiology training an d a greater numberwho have only had a U.S. Air Force 4-hour passenger class.

Unit standing operating procedures should adhere to ARs 95-1 and40-8. High alt itude flights should bescheduled 24 hours apart if possiblebut never less than 12 hours apart.Personnel should never fly less than24 hours after scuba diving. Personnel must prebreathe 100 percent oxygen for 30 minutes at ground levelprior to flight at or above 18,000 feetMSL. Prebreath ing 100 percent oxygen for 30 minutes will reduce the nitrogen level in the body by 30 percent,greatly reducing the chance of decompression sickness. Encouragecrewmembers to remain on 100 percent oxygen throughout landing rolland until engine shutdown. This extended oxygen period will continue tofacilitate removal of nitrogen to reduce the risk of decompression sickness. An additional benefit of remaining on 100 percent oxygenduring night landings is that the oxy-

gen will improve night vision.Another important factor to consider is exercise; this is not covered byregulations. A review ofthe literatureshows a correlation between exercise

and an increased rate of decompression sickness. It has been a long standing policy in both the Air Force andArmy to prohibit any exercise for 12hours after an altitude chamber exposure. Another useful suggestion forcommanders would be to restrict vigorous exercise immediately prior to amission since the subsequent dehydration may provide some additionalrisk.

The current weight control policyof the Army eliminates th e majorcontributing factor of obesity. Bodyfa t holds seven times the amount ofnitrogen as muscle. Therefore, itwould be beneficial for commandersto encourage an individually orientedexercise program that will increaselean body mass and decrease bodyfat. Such a program is outlined in DAPamphlet 350-18, "The IndividualHandbook on Physical Fitness," orconsult the flight surgeon ordietician.

TreatmentAs serious as decompression sickness can be, it is easily treated. Theimportant factor is early detectionand treatment. With early detectionand treatment, decompression sickness is of minimal threat to anaviator's flight status. At the first signof symptoms the aviator should beplaced on 100 percent oxygenthrough an aviator's mask andshould remain on oxygen until treatment by the flight surgeon.



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RIGHT (left to right): MAJ Mitchell, SFCLacey and SSG Olsen are testing thehyperbaric chamber.BELOW: Inside the chamber, SGTSchweyer (left) is administeredtreatment for decompression sicknessby SFC Yeager (right).

The normal treatment for decompression sickness is recompression ina hyperbaric (diving) chamber. Withexpeditious recompression, 100 percent resolution of the decompressionsickness can be expected. Expeditiousrecompression does not happen byaccident. Hyperbaric chambers arenot located near most Army airfields.Coordination should be made withthe local flight surgeon to form a de-

compression sickness evacuationplan. The local flight surgeon must beaware of all units in his patient population with a high altitude mission.An Army aviator is too valuable a

combat multiplier to be lost to decompression sickness. This is especially true since decompression sickness is so easily prevented by goodleadership, obedience of regulationsand good common sense. So, if you

REFERENCES1. Davis J, Sheffield P, Schukecht I, Heimbach R, DunnJ, Douglas G, and Anderson K. " Altitude DecompressionSickness: Hyperbaric Therapy Results in 145 Cases."Aviat. Space Environ. Med, 1977, 48:722-730.2. DavisJ, Tager R, Polkovits H, and Workman R. " Neurological Decompression Sickness: Report of Two Casesat Minimal Altitudes With Subsequent Seizures." Aero-space Medicine, 1971 , 42:85-88.3. Dixon G, Adams J, and Harvey W. " DecompressionSickness and Intravenous Bubble Formation Using a 7 .8psia Simulated Pressure-Suit Environment. " Aviat.Space Environ. Med, 1986,57:223-227.4. Fryer,D. " Decompression Sickness at 18 ,500 Feet: ACase History With Comment. " Aerospace Medicine ,1964, 35:479-480.5. Gernhardt, M: " Tissue Gas Bubble Dynamics DuringHypobaric Exposures." Fifteenth Intersociety Conference on Environmental Systems.San FranCiSCO , CA, July1985.

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6. Houston, C. " Occurrence of Bends, Scotomata andHemianopsia at Altitudes Below 20,000 Feet. " AviationMedicine, 1947,18 :165-168.7. Marlowe, B. " The Bends: Decompression Sickness atCabin Altitudes Above FL 180, a 1985 Update." Air ForceSafety Journal, 1986, 5:14-18.8. Odland, L. " Fatal Decompression Illness at an Altitudeof 22,000 Feet. " Aerospace Medicine , 1959, 30:840-846.9. Piwinski S,Cassingham R, MillsJ,Sippo A, Mitchell R,and Jenkins E . " Decompression Sickness Inc idenceOver 63 Months of Hybobaric Chamber Operations ."AviatSpace Environ. Med, 1986, 57:2097-1100.10. Piwinski S, Mitchell R, Goforth G, Schwartz H, andButler F. " A Blitz of Bends: Decompression Sickness inFour Students After Hypobaric Chamber Training." Aviat.Space Environ. Med , 1986, 57: 600-602 .11 . Robie R, Lovell F, and Townsend F. " PathelogicalFindings in Three Cases of Decompression Sickness."Aerospace Medicine , 1960, 31 :885-896.

or a member of your unit developssymptoms of decompression sickness, alert your flight surgeon rightaway. It is impor tant tha t a flight surgeon be notified. Regular doctors donot receive the same training as flightsurgeons in the diagnosis and treatment of decompression sickness.

Remember, early diagnosis andtreatment is the key to successful resolution of decompression sickness.

ABOUT THE AUTHORSMajor Robert A. Mitchell is aMedical Service Corps SeniorAviator. Until August 1986 hewas chief of the AeromedicalFactors Division, U.S. Army

School of Medicine, Ft. Rucker,AL. He attended the U.S. AirForce Clinical HyperbaricPhysiology Fellowship, BrooksAFB, TX.Major John McNamara, M.D.,is an Army flight surgeon withpast assignments in Korea andHonduras. He has treated theonly two reported cases ofoperationally induced altitudedecompreSSion sickness InArmy aviators.

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WIRE DETECTION:History and FutureMr. Alfred KleiderThe views expressed in this article are those of the author and are not necessarily those of the Department of the Army, the U.S. Army AvionicsResearch and Development Activity or the Army Safety Center .

This is the final article in a four-part series on detection and avoidance of wire hazards. In the firstthree articles, CW4 Robert J. Rendzio addressed people and equipment limitations that affect ourabil ity to cope wi th this hazard to safe flight operations. In this article, Mr. Alfred Kleider, anelectronics engineer with the U.S. Army Avionics Research and Development Activity, discusses thehistory of wire strike protection for Army aircraft, the evolution of wire detectors, and what the futuremay hold in wire avoidance systems.

RECOGNITIONOFwires as a class of obstacle, andas the ultimate obstacle for nap-of-the-earth (NOE) helicopter operations, dates back to 1960. The proliferationof this class of obstacle and the lack of an adequate detection device continued until the late 1970s when wirecutters were introduced as the proposed solution to thisproblem. Before then, wire detection was near the top ofthe Army's priorities in regard to barriers in NOE operations. After the introduction ofwire cutters, the priorityofwire detection devices fell to place 389out of400 in theArmy's list ofneeds. It was ironic that this occurred at thevery time when the solution to detection of 3 mm (1/8-inch) wires at ranges ofmore than 300 meters finally became something that could be realized.In the early 1960s, tests demonstrated X-Band radar

could not provide reliable reflections from wire obstacles. Experiments with shorter wavelength radar deviceswere conducted at the U.S. Army ElectronicsCommandat Ft. Monmouth, NJ, in the late 1960s with similarly disappointing results. In 1964, the first laser-based wire detection device was proposed by Honeywell: the laser

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in flight obstacle detector (LIOD). This proposal was thefirst time wire size and minimum range of interest weredefined (l/8-inch diameter at 1,000 feet), and this was thefirst time a laser-based solution to this problem was offered. The LIOD used an Nd YAG laser operating at awavelength of 1.06 microns (infrared). The LIOD failedto provide the necessary field of view (FOV) in a reliablemanner. This was for the most part a condit ion directlyrelated to the infancy of laser devices.Results of the short wavelength (3 mm to 4 mm) radardevices revealed that the wires were highly specular at thiswavelength (i.e., the illuminating signal is reflected intospace and not back toward the receiver), and the reflectedsignals were received only when the wires were close toperpendicular to the signal emitted from the transmitter.These results reinforced the theories that supported useof devices whose illuminating radiation was of muchshor ter wavelength, such as visual optical and infraredwavelengths. In this class of devices, the laser (an acronym for light amplification by stimulated emission of radiation) was seen as the best source for these purposes.

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AHIPAMCAVRADACCDFOVHELMORLHXLlODLOTAWSNOETVWOWS

GLOSSARYArmy Helicopter ImprovementProgramArmy Materiel CommandArmy Avionics Research andDevelopment Activitycharge-coupled devicefield of viewheterodyne laser multifaction opticalradarlight helicopter experimentallaser inflight obstacle detectorLaser Obstacle Terrain AvoidanceWarning Systemnap-of-the-earthtelevisionWire Obstacle Warning System

FIGURE 1: Gated low light level TV system in conjunctionwith a GaAs laser illumin ator is shown strapped to an XM-23gun mount on a UH-1 helicopter.

FIGURE 2: While a helicopter hovers, wires as small asl/8-inch can be seen on the screen in the cockpit at a rangeof up to 1 kilometer.

JANUARY 1988

The properties of lasers-high intensity, small beam divergence and high degree of monochromaticity-madethem ideal sources for attacking the problem.In 1973, tests were undertaken with a gated low lightlevel television (TV) system operation in conjunctionwith a GaAs laser illuminator l as shown in figure 1. Thedevice was strapped down to an XM-23 gun mount on a

UH-l Huey. Wires as small as 1 8-inch were observed ona TV screen in the cockpit, at a range of up to 1 kilometer,while hovering (figure 2).Also in 1973, a dual approach to the wire detectionproblem was undertaken at the Avionics Laboratory atFt. Monmouth. In one case, development of asingle-purpose wire detection device based upon the incorporation of a charge-coupled device (CCD) was instituted. Simultaneously, as a means of providing a morecost-effective approach, wire detection was included asone of several functions tha t could be provided by a heterodyne carbon dioxide laser operating at 10.6 microns.This latter system, Laser Obstacle/Terrain AvoidanceWarning System (LOTAWS)2 (figure 3, page 14), waseye-safe and operated in an atmospheric window thatprovided better transmission and reception in inclementweather. The CCD-based Wire Obstacle Warning System (WOWS)3 4 provided automatic wire detection andrecognition without an a ttendant crewmember. Figure 4(pages 14 and 15) illustrates the WOWS.Costs were the decisive criteria for further developments; and a new, lighter-weight, multifunction CO2laser system was designed and fabricated by United Technologies Research Laboratories in East Hartford, CT, in1980. The heterodyne laser multifunction optical radar(HELMOR)5 6 was designed to provide terrain follow-

1Kleider, A., ' 'Wire Obstacle Detection Techniques for Rotary Wing Aircraft,"Proceedings 9th Army Science Conference, West Point, NY, 1974.

2DeiBoca, R. and Mongeon, R., " Multifunction CO2 Heterodyning Laser Radar forLow Level Tactical Operations," National Aerospace and Electronics Conference '79,May 1979.

3Kleehammer , Hunt, and Kleider, " Applications of a Charge-Coupled Device Sensorfor Automatic Detection and Recognition of Wirelike Objects ," Proceedings SPIE(Smart Sensors), April 1979.

4Kleider , A. , " Wire Obstacle Warning System," U.S. Patent No. 4,068,124,10January 1978 (Assigned U.S. Army).

SSilverman, Green, et. al. ; " Multifunction CO2 NOE Sensor," Technical ReportAVRADCOM 85-E-1 , May 1984.

6Kleider, A. " A Multifunction CO2 NOE Sensor System-An Overview and StatusReport, " IRIS Conference, White Oaks, MD , October 1982.

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FIGURE 3: Laser Obstacle/Terrain Avoidance WarningSystem (LOTAWS).

ing, precision Doppler navigation, precision hover andwire detection for helicopters operating in an NOE regime (figure 5, page 16). Ground tests demonstrated thewire detection capabilities of the HELM0 R, and the unitwas installed in a UH-60 Black Hawk. Ground tests withHELMOR demonstrated detection of 1/4-inch wires,both electrical conductors and nonconductors, at rangesof 300 meters. The laser system was flight-tested andshown to be operable in the vibration environment of ahelicopter; however, lack of funds precluded completionof the flight tests.

In the first half of 1986, two events caused renewed interest in wire detection devices: A message was receivedin Army Avionics Research and Development Activity(AVRADA) from Eighth Army in Korea requesting information about the availability of wire detection devices, and an AH-64 Apache was heavily damaged in awire strike. The level of interest in wire detection deviceswas elevated to the Army Materiel Command (AM C). Asa result, detailed briefings on wire detectors were conducted for the deputy commander and deputy chief ofstaff for readiness at AMC.

The task for developing a program to provide theArmy with a wire/wire-like obstacle detection and avoidance system has been assigned to the Center for Night Vision and Electro-Optics at Ft. Belvoir, VA. The need forsuch a system has been established clearly in the product

14

improvement plans for the Army's light helicopter experimental (LHX) and the V -22 Osprey tilt rotor aircraft. Itis most likely that the system to be fielded initially will bea single-purpose device for detection and avoidance of abroad class of obstacles, including wires. Weight and sizealong with functional parameters relating to range, FOV,signal processing rates and display requirements areother essential elements to be considered in designingsuch a system.Weight of the system is the driving design parameter .For an obstacle avoidance system to be given serious consideration, its weight should not exceed45 pounds, with adesign goal of less than 30 pounds. It is clear that someform of laser device is necessary if wires and wire-like objects are to be included in the list of obstacles. The exactlaser technology that will be used has not been fixed; however, the need for covertness and efficient operation,along with the requirements for eye-safe operation, restrict the lasers to be considered as candidates. The CO2laser, which operates at a wavelength of 10.6 microns, isthe most mature technology at this time. These lasershave advanced to a point where a 5- to 1O-watt, air-cooledsystem can be constructed in a package weighing less than



17/48

8 pounds. Operationa l life an d shelf life of these lasershave been established and verified in practice.

Other laser technologies including Raman-shifted,neodymium lasers that operate at an eye-safe, 1.5 micronwavelength also are being looked at with interest. Thisparticular technology is less mature than the CO2 but hasgreat potential for lightweight system uses.

The impact of weight restrictions upon system performance for an obstacle detection/ avoidance device is twofold. The operational detection range is directly related tothe laser power output. Laser power is strongly weight dependent since higher power usually involves liquid cooling and large heat exchangers. The second factor that ismost affected by weight consideration is the optical FOV.The greater the FOV, the larger the optics and the scanners. Larger implies heavier. Thus the range (laser power)and FOV are the principal areas of compromise in aweight-limited system.

When the entire set of factors is considered in atradeoff study where operational performance, weight,size and cost effectiveness are the principal parameters,the results show that a high degree of protection againstwire strikes can be provided with today 's technology. Re-

JANUARY 1988

alistically, 100-percent protection cannot be achieved;however, wire detection devices coupled with wire cuttersare a realistic solution to today's wire strike losses. Whenused concurrently, there is no reason that a 9O-percent reduct ion in wire strike accidents cannot occur. Trainingmissions that include NOE in both daylight and nighttime environments are conducted in special areas whereobstacles and wires are clearly indicated on missionmaps. In the case of wire obstacles, highly coloredspheres (about 12 inches in diameter) are strategicallyplaced on each span of wire. For long spans , several such"attention grabbers" are included to ensure visibility. Inthe real-world situation, and esp.!cially in the combat environment, no such pilot aids can be expected to bepresent. I f he Army helicopter is to survive in an NOE environment, a wire obstacle warning and avoidance devicemust be included in the mission equipment package.The problems of wire strikes are real, and they are sureto increase in the future . The tactical dictates for NOE operation are well unders tood. The emergence of new andhighly sophisticated aircraft such as the Apache, AHIP(Army Helicopter Improvement Program) and the LH Xfamily of next generation helicopters makes the acquisi-

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FIGURE 5: Heterodyne laser mul tifunction radar (HELMOR)(top), a closeup view of HELMOR (center) and an inside viewof UH-60 avionics compartment showing mounting ofHELMOR (bottom).

tion of an obstacle warning and avoidance system a priority item. The costs of these aircraf t and the survival oftheir crews will depend heavily on providing such a sys-

16

tern. Wire cutters are cheap insurance, but as shown in thearticle in the December 1987 issue of A viation Digest,they are not the state-of-the-art solution. A laser-baseddevice that provides a warning to the pilot and, in instances where adequate displays are available, actual 10-cations for such obstacles relative to the aircraft headingcan complement the wire cutters by providing the capability of avoiding wires entirely. 7CiF +-

ABOUT THE AUTHORMr. Alfred Klelder is an electronics engineer with

the Advanced Systems Branch of the IntegrationDivision, AVRADA, at Ft. Monmouth, NJ. Mr.Klelder has been with this activi ty since 1972.Prior to that time, he spent 19 years in industry inresearch and development of lasers and lasersystems. His first experience with the problems ofwire obstacle detection dates back to 1964, andsince that time he has been deeply involved withthis problem area.

Mr. Kleider is a graduate of the University ofOklahoma where he earned a BS in engineeringphysics and an MS in physics. He is a member ofthe Optical Society of America and the AmericanAssociation for Artificial Intelligence. Mr. Klelderhas published 15 technical articles and holdsseveral patents. One of these patents Is for a wireobstacle system.



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PEARl!SPersonal Equipment And Rescue/survival Lowdown

ALSE School NewsThe instructors at the aviation life support equipment

(ALSE) school, Ft. Eustis, VA, are going to be busy in fiscal year (FY) 1988. The current schedule calls for 20ALSE specialist and 14 supervisor classes. FY 1988 students will benefit from the new training on the helicopteroxygen system and the M-43 mask. Other new trainingmay include the PRC-90-2 and PRC-112 survival radios,the TS-24B test set, the new survival vest and the aircraftmodular survival system.

Slots for the school ca n be secured from the TotalArmy Personnel Agency (TAPA) on DA Form 4187through your chain of command. Requests should specify either course number, 600-ASIQ2, or course title,Aviation Life Support System Supervisor. Enlisted personnel requests should go to the Commander TAPA,ATIN: DAPC-APT F, 200 Stovall Street, Alexandria,VA 22332-0400. Warrant officer requests also should goto TAPA, ATTN: DAPC-OPW -A V, 200 StovallStreet, Alexandria, VA 22332-0400. Civilian personneldesiring this training should submit requests throughtheir servicing Civilian Personnel Office.

Commanders are reminded that the ALSE programneeds your full and enthusiastic suppor t in order to function properly as outlined in AR 95-17, "The Army Aviation Life Support System Program."

Shoulder Harness InjuryA recent OH-58 Kiowa helicopter accident revealedthat the shoulder harness did its restraint job too well.The shoulder harness was tightly held against the lensatic

pocket in the survival vest pocket and caused a painfulbruise to the injured person's clavicle bone. A "fix" recommended by Natick Research and Development Engineering Center (NRDEC) was to insert a 1/4-inch foamrubber pad, nat ional stock number (NSN)9330-00-573-7379, into the compass pocket to alleviateand minimize such problems from occurring in the fu-

JANUARY 1988

ture. Point of contact (POC) at NRDEC is Mr. ChuckBraga, AUTOVON 256-5449.

ALSE/AEROMED NewsletterPlease notice the title of this new publication. It is another much needed publication that is put out by the HQAMCPOC.Several months ago we announced that LTC McClelland was the HQ AMC POC for ALSE. This action is adistinct advantage as nowwe have one more contact to assist in the ALSE area. PEARL's will still function as always for worldwide information and data in the ArmyAviation Digest's PEARL's articles.

You can reach LTC McClelland by callingAUTOVON 284-989119892 or by writing AMCRE-AV,5001 Eisenhower Avenue, Alexandria, VA 22333-0001.Your participation in this new newsletter is encouraged.

Shipping Flight Helmets as BaggageFlight helmets are being damaged when shipped as airline baggage. Aircrew personnel are using the aircrew kitbag with the flight helmet placed inside with clothing. Wemust stop this practice to preclude further damage to a vital item. Flight helmets will be carried as carry-on luggageand stowed in the overhead baggage compartment . Thehelmet bag will be used to carry the helmet from locker toaircraft, TDY or any other time it is required.

Jacket, Flyer's, CWU-4S/P, HeavyweightEffective 1 May 1987, the Defense Personnel SupportCenter (RIC S9T) accepted funded requisitions for the

jacket, flyer's, CWU-45/P, heavyweight, NSN8415-00-310-1111 series. This jacket replaced the jacket,flyer's, N2B, heavyweight, NSN 8415-00-118-7569,7573, 7574 and 7587, sized S, M, L and XL. The CWU-45/P, made of Nomex fabric, provides flame resistance

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that the N2B did not. The unit price of the jacket is$110.00, and the unit of issue is EA. NSNs, sizingandrecommended tariff are as follows:TarriffJacket, Flyer's Size per 1,0008415-00-310-1111 S-34-36 151-1123 M-38-40 363-1133 L-42-44 325-1140 XL-46-48 161

The basis of ssue for jacket, CWU-45/P, is identical tothat of the replaced jacket, N2B, found in CTA 50-900under LIN L14978. The CWU-45/P jacket, flyer's, is tobe worn with the hood, flyer's, NSN 8415-01-167-7242series.

Control led Medical Items/Components ofAviation Survival KitsAR 40-61, paragraph 3-62, gives aircrew personnelgood guidance on how subject items are issued and controlled. In summary, controlled items must be in the survival kits at all times to ensure availability for use bycrewmembers when emergency survival situations occur.Replacement of expired controlled items is authorized bysupply officers who are accountable for the kits. At unitlevel these kits normally will be in the possession of personnel authorized kits for aviation opera tions. Kits will

be secured in the same manner as prescribed for otherALSE; such as in a locked room, crate or individuallocker preferably in the aircrew personnel survivalvest/first aid kit.

ELT Finds/SavesEarly afternoon on 24 September 1987, the MissouriWing, Civil Air Patrol (CAP), was alerted by the ScottAir Force Rescue Coordination Center, Scott Air ForceBase, IL, of a missing, downed aircraf t in southeast Missouri, the Bootheel area.A student pilot on a cross-country flight had becomedisoriented and radioed back to his instructor for help.While the instructor was trying to help, the student ran

out of gas and was forced to land in a corn field. Althoughthe student was not hurt the aircraft did sustain damages.The student was told to activate the emergency locatortransmitter (ELT) onboard the aircraft. CPT McDowlfrom the Bootheel stationed CAP aircraft was told byMAl Garner to take of f and search for the downed aircraft. After CPT McDowl flew for about 30 minutes he

18

picked up the ELT signal. With the special homing equipment onboard he flew directly to the downed aircraft. Atabout the same time, Scott AFB Rescue Center alertedMAl Garner of a faint signal emanating from the southwest St. Louis County area. Knowing that the downedaircraft had been found, they flew back to the St. Louisarea and began to search for the faint ELT signal. Theyfound the signal was coming from a landfill off SulpherSpring Road, south of Big Bend. A ground search partyarrived at the landfill and, using portable homing equipment, found the signal was coming from under theground. They asked landfill employees to take a bulldozer and remove some of the landfill. Soon a strongersignal was heard. Digging in the dir t and trash by hand,the transmitter was found and turned off. Apparently,someone thought the discard information on the batterymeant the ELT itself should be discarded. The ELT certainly did its thing even after it was discarded. Treat yourELT with tender loving care and it will certainly take careof you. (Credit for this article is given to THE INSIDER,GROUP II NEWSLETTER, Missouri Wing/CAP.)

Technician Offers Tips for Effective ALSE SystemAs aviation equipment becomes more sophisticated,the demands on the ALSE system will increase.Yet no military occupational specialty (MOS) exists inthe U.S. Army for an ALSE technician. Often, it is an additional duty assignment.As a result, if a soldier isn't school trained in ALSE,there's not a lot of guidance to help in establishing or

maintaining an ALSE shop.For those persons, Minnesota's only school-trainedALSE technician working in the ALSE field-SergeantNyleen Mullally-offers several tips on setting up and

maintaining an effective and efficient ALSE system.The 12-year National Guard veteran supports about

185 persons on flight status in the Minnesota Army National Guard .Her ALSE shop received a glowing report during a recent Regional Accident Prevention Survey by the Austin,TX, Army Aviation Support Facility.SGT Mullally has worked in ALSE for 5 years. In 1984,she attended the 6-week ALSE course at Ft. Eustis, VA.She is also MOS-trained as a flight operations specialist,in utility helicopter repai r, and has attended the ColdWeather Survival School in Ely, MN, and the OverwaterSurvival Course in San Diego, CA.As an ALSE technician, she handles survival radios,survival vests, flight helmets, cold weather survival kits,aircraft first aid kits, personal flotation devices, flight



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clothing and survival training. She handles propertybook transact ions for flight clothing, trains ALSE personnel, and instructs on the use of survival equipment. Inaddit ion, she is responsible for issuing, inspecting, repairing, replacing and turning in survival equipment.

"Since there 's no MOS, it's really difficult at times tofind help-to know who to call or how to get advice," sheexplained.First and most impor tant , she said, is to get the commander's support and assistance for the ALSE system.This includes having properly trained personnel, and nothaving untrained people working on survival equipment.

The next step is to at tend the ALSE course.Organizing the ALSE shop is also important , so "youcan find what you need and not waste time," she said.This includes setting up a library of reference material, afile system and parts inventory.

In her ALSE shop, rows of survival equipment components line the shelves. In the center are work desks anda large, handy workbench.

Her reference library occupies shelf space near thedesks, and the filing system is also easily accessible."I finally sat down and did it, and I can't believe how

nice and organized it is. I fyou don't have adequate working area, start asking for it," she stated.

Any ALSE technician would enjoy workingin this well-organized ALSE shop. Howeffective your ALSE shop is depends onhow efficient your system is maintained.photographs by Benjamin Martel

Since there are no annual gatherings of ALSE personnel, an informal network of ALSE technicians hasevolved. This network can prove valuable in learningmore about the ALSE system and in solving related problems.

"A good source of support on the ALSE system is theALSE Center at the Aviat ion Systems Command in St.Louis, MO. Regional Army Aviation offices also canrender assistance," she said.More emphasis should be placed on the ALSE technician's familiarity with survival training, not only how touse the equipment, but what to do.

SGT Mullally recently taught a week-long course toMinnesota National Guard personnelon the basics of theALSE system. One day was devoted to a survival exercise, where participants set up shelters, broke out survivalkits, shot flares, used radios and built fires.

Sometimes, she said, she may be perceived as"Chicken Little," warning about following propersafety and survival procedures. But an apathy can develop about following proper safety measures. "Thattype of attitude is probably the biggest obstacle. There aretimes when that can be just as much of a detriment as notbeing able to get the supplies you need," stated SGTMullally. ~

If you have a question aboutpersonal equipment or rescue/survival gear, write PEARL'S, AMC Product Management Office, ATTN:AMCPM-ALSE, 4300 Goodfellow Blvd., St. Louis, MO 63120-1798 or call AUTOVON 693-3817or Commercial 314-263-3817.

JANUARY 1988 19


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US. lm

Directorate of Evaluation/Standardization t ~REPORT TO THE FIELD lVllT..STbDAlOlllTIOIr

Consolidation of 95-Series Army RegulationsMr. James P. WallDirectorate of Evaluation and StandardizationU.S. Army Aviation CenterFort Rucker, AL

AR 95-1 AND some other 95-series regulationshave been revised during the past year, and anotherrevision of these regulations will be published in thenear future.Consolidation of 95-series Army regulations, agoal of Army Aviation for more than 2 years, willbecome a reality when all bu t the joint Army, AirForce and Navy regulations are consolidated inthree volumes: AR 95-1, AR 95-2 and AR 95-3.This effort should not only reduce the number ofaviation regulations to three, but should bringabout some other changes that have long been desired. For example, aviators have asked which Federal Aviation Regulations (FAR) apply to theArmy. AR 95-1, Change 6 (paragraph 4-1a), indicates that specific paragraphs in FAR Part 91,subparts A and B, that do not exempt military aircraft or flight crewmembers, apply to flights in theNational Airspace System. This forces aviators tosearch through FAR Part 91 to find those para-graphs that do not exempt the military. There is always a possibility of overlooking applicable paragraphs, so why not provide a list of those that doapply to prevent this unnecessary search. Therefore,appendix B of the new consolidated AR 95-1 will include an extractofall applicable paragraphs ofFARPart 91.

AR 95-1, as we know it, will be purged of alladministrative-type provisions, e.g., operationalsupport airlift (OSA) and standardization, and will

pick up applicable portions of AR 95-17, "AviationLife Support Equipment," andAR95-16, "Weightand Balance." It will become a regulation that willbe used on a day-to-day basis by aviators and it willbe renamed "Flight Regulations."

AR 95-2 will combine six regulations to becomethe publication that is most applicable to air trafficcontrol, airspace, navigation facilities and airfields.Each of the old regulations will become a chapter ofthe new regulation and, except for paragraph numbers, remain virtually unchanged. Organizationsthat are the proponent for individual regulationswill continue as the proponent agency for individualchapters within the consolidated regulation.General provisions, aviation life support equipment, weight and balance, safety of flight messages,flight violations, OSA and standardization, thosethings that relate to the management of the ArmyAviation program, will appear in AR 95-3. In general, the material in this regulation will be used bycommand and staff to establish and manage programs that are essential for aviation training, standardization and maintenance. In addition to consolidating existing regulations, a chapter will beadded to provide guidance for scheduling and managing Army OSA assets.Each of the new regulations will be printed in theUPDA TE format, thereby eliminating the need topost changes. Changes will be made on cycles established by user needs. . . . . , I

DES welcomes your inquiries and requests to focus attention on an area of major mportance. Write to us at: Commander, U. S. Army Aviation Center, ATTN: ATZQ-ES, Ft. Rucker, AL 36362-5000; or call us at AUTOVON 558-3504 or Commercial 205-255-3504. Afterduty hourscall Ft. Rucker Hotline, AUTOVON 558-6487 or Commercial 205-255-6487 and leave a message.

20 U.S. ARMY AVIATION DIGEST


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EDITORRETIRESM r. Richard K. Tierney, editor, U. S. Army AviationDigest, since April 1968 , will retire from Federal service inFebruary 1988 after 28 years with the U.S. Army at Ft.

Rucker, AL.In January 1960, Mr. Tierney joined the Digest as awriter. Almost immediately, he drew upon his wartimeexperiences and personal vision of the potential application for Army aircraft. He had served in Korea as a Marine infantryman and had seen first-hand the value of he1-icopters and light aircraft in support of ground combatunits in wartime. After these wartime experiences, he hadbecome a newspaper journalist, working as a sports reporter, sports editor and a copy editor. Writing for theDigest, he developed a series of articles on the need forarmed helicopters on the battlefield, which appeared firstin the May 1960 issue.

An early leader of efforts in the 1960s to protect ahandful of deteriorating Army aircraft of historicalvalue, Mr. Tierney was responsible for actions that ledto the establishment of the U.S. Army Aviation Museum. He is also credited with being the "impetus" forthe Ft. Rucker Historical Society. In addition, in 1962,working with Dr. Stetson Conn, then Chief of MilitaryHistory at Department of the Army, Mr. Tierney developed the first Ft. Rucker Historical Report. This reporthas become an annual report of significant activities.

JANUARY 1988

Mr. Tierney compiled and wrote' The Army AviationStory," published in book form in 1963, providing thefirst comprehensive history of Army Aviation. In theearly 1970s, he published' The Armed Helicopter Story"in a series of A viation Digest articles. As an early advocate of helicopter capabilities beyond ground combat, hepublished an "Air-to-Air Combat" article in the Digestin the July 1974 issue. In 1978, he developed a series ofarticles that were to pave the way for the establishment ofArmy Aviation as a separate branch. These articles addressed the key issues related to that development.

In 1982, Mr. Tierney published Forty Years ojArmyAviation, a booklet covering the developing concept ofArmy Aviation, a concept born on 6 June 1942 when theWar Department approved organic aviation for U.S.Army Field Artillery units. Included is a history of thegrowth of the Army Aviation training program, whichstarted in July 1942; the establishment of the Army Aviation School at Ft. Sill, OK, in January 1953; and theschool's new home at Camp Rucker, AL, in December1954. He vividly describes Army Aviation's entry intocombat in November 1942, in North Africa, and its par tlater in the Korean and Vietnam Wars. He then discussesthe Army's various armed helicopter experiments conducted in the late 1940s through the early 1980s with theemergence of he AH 1S fully modernized Cobra and theAH-64 Apache attack helicopter. Concluding with theroles and missions of Army Aviation of more than 40years, he writes, "People of Army Aviation are continually dedicated to accomplishing their missions in a professional manner. It all spells success. Such is Army Aviation today-Above the Best."

The A viation Digest has become more than a merechronicle of developments in Army Aviation throughMr. Tierney's 20-year leadership. Recently decorated bythe Secretary of the Army John O. Marsh Jr., on 18 November 1987, in ceremonies at the Pentagon, Washington, DC, with the Department of the Army Decorationfor Exceptional Civilian Service, Mr. Tierney was citedfor his long dedication and major contributions to ArmyAviation. Through his efforts as staff writer, editor,managing editor and historian, he not only distinguishedhimself but enabled the magazine to become a spearheadfor evolutionary concepts such as armed helicopters, helicopter close air support and, more recently, helicopterair-to-air combat.Mr. Tierney will remain in Ozark, AL, after his retirement and continue to compile and write the history ofArmy Aviation. The staf f of the A viation Digest and hismany friends in the Army Aviation community wish himmuch success in his retirement and these endeavors.

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AVIATION PERSONNEL NOTES

Warrant Officer (WO) Personnel Policy ChangesEffective 1 October 1987, WO policy was changed to

establish a mandatory Regular Army (RA) integrationpoint. This means that other than Regular Army (OTRA)CW2s selected for promotion to CW3, Army of th eUnited States, will be automatically considered for an RAappointment by Headquarters, Department of th eArmy. Eligible officers tendered an RA appointment willbe required to accept or decline the office prior to promotion to CW3. Warrant officers who decline RA integration will be separated from active service if their ActiveDuty tour as a WO started on or after 1 October 1987.Those who decline will not be separated if their WO Active Duty tours star ted before 1 October 1987, and theyhave completed less than 20 years of active federal service(AFS).

Other policy changes include an increase in obligatedvoluntary (OBV) service periods for nonrated WOs. Allnewly appointed WOs now incur a 5-year OBV periodupon appointment. This action aligns all WO OBV service at 5 years, both rated and nonrated.

Another change is the elimination of the conditionalvoluntary indefinite (CVI) process for WOs. Now allWOs will be considered automatically for voluntary indefinite (VI) status during the last year of OBV service.Warrant officers who have already been selected for CVIhave been sent letters indicating that their status has beenchanged to VI.

A final change of note involves the separation policyfor OTRA WOs. There is now no fixed maximum servicepoint for OTRA WOls and CW2s; separation will be a

22

function of VI and promotion to CW3. All OTRA CW3sand CW4s whose Active Duty tour as a WO started before 1 October 1987 and who have not integrated into theRA will still be released mandatorily f rom Active Duty at20 years AFS.

Emphasis on Reenlistment NeededReenlistment of first-term soldiers in Aviation Branch

military occupational specialties (MOSs) may be a criticalfactor in the continued health ofthe branch for fiscal year1988. The Army Recruiting Command may not be able tomeet all of the aviation requirements this year due to severe budget cuts. Recruiting Command shortages can beeffectively offset, however, by increasing the reenlistment of first-term soldiers in aviation MOSs.

Currently several aviation MOSs are below the Armyaverage in reenlistment rates. With emphasis at all command levels, each aviation related MOS can exceed theaverage. To assist in retaining quality soldiers, the Aviation Branch Chief has approved actions designed to balance the promotion opportunity across the enlisted structure of the branch. Reenlistment options also help retainquality soldiers. The Aviation Branch has 10 MOSs eligible for reenlistment bonuses. Some aviation soldierscan qualify for degree completion if study is specificallyrelated to their MOS. The station-of-choice option is another popular tool successfully used to reenlist aviationsoldiers.

These reenlistment options, when combined with thebalanced promotion opportunity and stressing the new



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and innovative technology used by Army Aviation, willconvince first -termers to stay in the Aviation Branch. Thebranch has quality soldiers; the challenge this FY is tokeep them.Army Aviation Personnel Plan (A2p2)

The initial copies of the newly completed A2p2 weredistributed at the Aviation Commander's ConferenceheldatFt. Rucker ,AL, 1 to 4 December 1987. TheA2p2,while complementing the Aviation Modernization Plan,is a tool the Aviation Branch is using to review the past, realistically evaluate the present and logically project future needs respecting personnel issues.

The Aviation Branch and the Army are now better ableto be proactive when making decisions in the personnelarena because of A2p2. Standardizationof accession andprofessional development programs, as outlined inA2p2, will help stabilize actions within those programsand bring about a better managed aviation force.

Regulating the accession or professional developmentprograms alone will not solve personnel managementproblems and is why A2p2 addresses all eight ofthe life cy-cle functions of personnel proponency (to include structure, individual training and education, distribution, deployment, sustainment and separation).

Although much of A 2p2is a "how to" for the personnel proponent business, much is useful for commandersat brigade and batta lion levels. For example, the careerprogression models in the professional developmentchapter are valuable guides for mentoring.

Commanders who have yet to obtain a copy of A2p2can do so by writing Commander, USAAVNC, ATIN:ATZQ-DAP-PS, Ft. Rucker, AL 36362-5000; or callingMrs. Jean Roebuck or CW4 Clifford Brown atAUTOVON 558-5706/4313, Commercial 205-255-5706/4313

Flight School NewsAn October 1987 message to the field clarified the age

requirement for Active Duty flight school applicants.The message notes that flight school applicants must be18 years ofage but not older than 29 years of age (must nothave reached their 30th birthdate).

A new Flight Aptitude Selection Test (FAST) wasmailed to the field in October 1987. Called the AlternateFAST (A-FAST), it replaces the current R-FAST. In es-sence it is a revised and updated version of previous testsand comes in two versions, A and B. Applicants who failthe A-FAST will be allowed to take the alternate versiononce, as a retake, but not sooner than 6 months from taking the initial test. Applicants passing the A-FAST thefirst time are not allowed any retakes to obtain a higherscore.

Army inservice aviation warrant officer candidate accessions are increasing. In the past, "high school to flightschool" (civilian) applicants were accessed at a rate ofabout 75 percent, whereas inservice applicants were accessed at about 25 percent. The accession mixtu re willnow be 50 percent/50 percent in order to access equallyfrom both groups. ~

u.s. Army Class A Aviation Flight MishapsArmy Total Cost

Number Flying Hours Rate Fatalities (in millions)FY 87 (through 31 January) 11 511,893 2.15 13 $32.4FY 88 (through 31 January) 6 511,893* 1.17 0 $10.6

estimated

JANUARY 1988 23


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24

Thisseventh article in theseries on theAH-64AApache aircraft addresses theelectrical, digitalau-tomatic stabilization equipment and utility systems. The information contained here isfor amiliarization only and must not be used to operate ormaintain the aircraft.



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Mr. Ron BrunelleMr. Philip A. Mooney

Electrical Power Generation and Distribution System

THIS SYSTEM (figure 1) suppliesall the alternating current (ac) and direct current (dc) power required tooperate the systems on the AH-64Apache. It provides power to the busof a failed generator or transformerrectifier (T IR) unit via automaticswitching, and it automatically connects the bat tery to the dc emergencybus if total electrical failure occurs.The two self-excited ac generatorsare mounted to the forward left andright sides of the main transmission.They are driven through the accessory gearbox (AGB) by either theauxiliary power unit (APU) or themain transmission, and their outputsare controlled by generator controlunits (GCUs). Each generator powersone ac bus. I f a generator failure occurs, then the operational generatorcan supply all power required by bothac buses. The GCUs, located in theelectrical power distribution center,monitor and control generator operations and isolate a faulty generator.Once a GCU isolates a faulty generator, it will latch that generator into theof/position (anticycling) and illuminate the respective generator failurelight.The pilot controls the generatorsby using the generator co n trolswitches located on the electricalpower control panel. Selecting thetest position will test generator output without putting the generator under a load condition.

The squat switch, located on theleft forward avionics bay (F AB) just

JANUARY 1988

~ .i.I?'liiiJiWMI;"t.t.i!MGENERATOR EXTERNAL

GROUNO TRANSFORMER NO 2 POWERSERVICE _P_OW_E_R_ _ ~ _ _ R.,ECTlFWERO. 2 BATTERY RE/CEPTACLETILITY OISTRIBUTIONRECEPTACLE ~ cm"

[ , , , : ~ y = - ~ : : : ~ : :_____ ~ - = - - = - - = - = - - r ~ ~ ~ ~ ; : , ~ : ' POW"PG BATT

OVERRIDE

PILOTs POWER GENERATORCONTROL PANEL NO . 1

TRANSFORMERRECTIFIER NO. 1

FIGURE 1: Electrical component locations.

GROUNO SERVICEUTILITY RECEPTACLE

EXT PWR CONTACTOR

FIGURE 2' Alternatmg current section operation

AC BUS 1

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I + - _ ~ r eAT OVRD -- ,

~ ~ NRMLOVRD

CPG POWER OUAORANT

PilOTs ElECTRICPOWER CONTROL PANEl

FROMBUS 2

LOCKOUT

FLY

FIGURE 3 Direct current section operation FIGURE 4 Direct current emergency section operation .

forward of the left main landing geartrailing arm pivot point, indicates tothe aircraft systems when the aircraftis on the ground. This information isthen used to enable/disable underfrequency protection. The squatswitch is activated when the aircraftweight is on the main landing gear.Aircraft electrical power is available externally for maintenance tasksby activating the ground service utility receptacle, which is located on theforward underside of the right forward avionics bay.There is one caution light for eachgenerator. These lights are illuminated by the respective GCU when agenerator has failed or has beenturned off.

In the ac section operation (figure2, page 25), generators are controlledby individual, three-position toggle

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switches. The GEN position enablesthe GCU to control generator output,while the OFF position disables/resets the GCU. I f a generator is isolated due to a fault condition, theswitch is then moved from the GENto OFF/RESET and back to GENposition. This commands the GCU toretest the generator output and, ifgood, to put the generator online.The momentary TEST position allows the pilot to check generator output without connecting the generatorto the bus. I f the GEN caution lightgoes out while the switch is held in theTEST position, the generator andGCU are functional under a no-loadcondition. I f he generatorwill not goonline, there is a fault in the electricalpower distribution system.The ac contactors route the generator output to the buses. I f a genera-

tor fails, the GCU will command thecontactor to apply power from theoperational generator to the bus ofthe failed generator. The contactorsprevent the generators from beingparalleled, and, by disabling the external power contactor, they also prevent paralleling the external powersource with the ai rcraft generators.GCU control of the ac system is automatic once the generator switch isturned on.The generator control unitwill illuminate the GEN caution light on thepilot's caution/warning (C/W) panelwhen it senses a generator failure orwhen the respective generator hasbeen turned OFF.The two T /Rs located in the maintransmission area receive 3-phase acpower from the ac buses and convertit to 28 volts direct current (Vde), with



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a nominal rating of 250 amps for eachT IR. Each unit normally suppliesone dc bus, and jointly powers a thirdbus and the dc emergency bus; how-ever, if one T IR fails, one unit canpower all dc buses and the dc emer-gency bus. The TIR outputs aremonitored by the dc contactor assem-bly, which also controls the TIR unitto the dc bus connections.Individual dc section componentfailures are displayed only to the pilotas RECT 1, RECT 2, HOT RECT 1and HOT RECT 2 indications on theC/W panel. I f both T IR units fail,FAIL ELECT SYSTEM will be dis-played on the copilot gunner's(CPG's) C/W panel.

The operation of the dc section(figure 3) is automatic and the pilothas no direct control. Direct currentoutput from the TIR will energize thedc contactor by routing dc power tothe respective dc bus, and dc emer-gency bus.

I f a TIR fails, the dc contactor willisolate the inoperative TIR unit androute power from the operating T IRto the dc bus of the failed TIR. Thecontactor also will illuminate the ap-propriate RECT caution light on thepilot's C/W panel.I f a dual TIR failure occurs, the dccontactor will isolate both TIR unitsfrom the dc buses. The pilofs C/W

panel will illuminate the FAILELECT SYSTEM indicator on theCPG's C/W panel when both RECTsegments are on.When the internal temperature ofaTIR reaches 190 degrees F, it will il-luminate a HOT RECT indicator onthe pilofsC/W panel. This is usuallyan indication of an internal fan fail-ure, but the TIR unit will continue tooperate.The heart of the dc emergency sec-tion components is a 24 Vdc, 13 amp-hour, 19 cell nickel cadmium batterythat is located in the aft avionics bay.The battery supplies electrical powerto enable APU starting (without ex-ternal power), and for dc emergencyoperation (figure 4) if total electricalfailure occurs.

JANUARY 1988

During normal operations, thebattery charger, located in the aft avi-onics bay, controls charging of thebattery, battery to dc emergency busconnections and battery and chargerfailure indications.The battery relay, located in the aftavionics bay, connects the battery tothe dc emergency bus on commandfrom the battery charger, when the

EX T PWR/BATT switch is in theBAIT position.The emergency bus diodes, locatedin the electric power distribution cen-ter, prevent feedback of dc powerfrom the dc emergency bus to the dcbuses.The EXT PWR/BATT switch, lo-cated on the pilot's electric powercontrol panel, enables the batterycharger to connect the battery to thedc emergency bus when it is in theBAIT position.

In an emergency situation, theCPG can disconnect the battery fromthe dc emergency bus by using theguarded battery override (BATOVRD) switch located on the powerlever quadrant.A hot battery (HOT BAT) light il-luminates on the pilot's C/W panelwhen battery internal temperatureexceeds 57 degrees 3 degrees C,when there is a defective cell or whena battery internal heater fails.When the charger is not chargingthe battery during a programedcharging cycle, the CHARGER lighton the pilot's C/W panel will be illu-minated.The CPG's BAT OVRD switch en-ables the pilot's EXT PWR/BATTswitch in the NRML position and dis-ables the pilot's EX T PWR/BATTswitch in the OVRD position. I f con-nected, the OVRD position discon-nects the battery from the dc emer-gencybus.

In the BATT position, the EXTPWR/BATT switch enables th echarger to connect the battery to thedc emergency bus if loss of inputpower to the charger occurs.The battery charger monitors dcbus No.1 and, when no voltage is

present, it energizes the battery relayto connect the battery to the dc emer-gency bus.When the charger fails to charge

the battery during a programedcharging cycle, the CHARGER lightwill be illuminated on the pilot'sC/Wpanel.

Battery charging is automaticwhen EXT PWR/BATT switch is ineither the BATT or OFF position. Inthe EXT PWR position, charging isinhibited. I t is important to ensurethis switch is in the BATT positionduring normal operations so that thebattery is charged for starting at re-mote locations.External 115 volts alternating cur-rent (Vac) power can be applied to theaircraft fo r systems checkout andstarting. It is applied through the ex-ternal power receptacle, located onthe right side 0 f the aircraft just af t theavionics bay access door.The power monitor, located on theright-hand side near the externalpower receptacle, monitors the inputexternal power for voltage, frequency and phase sequence. It alsocontrols the external power contac-tor.External power is applied to the acbuses by the external power contac-tor, which is located in the electricpower distribution center. The EXTPWR/BATT switch allows the pilotto enable the power monitor to ener-gize the external power contactor. I feither generator is online, the externalpower contactor is disabled.The external power reset switch, amonetary pushbutton switch locatedon the pilot's electric power panel, en-ables the pilot to reset the power mon-itor after the external power contac-tor has been deenergized due to someinput power fault. Once reset, thepower monitor attempts to reapplyexternal power to the helicopter'selectrical system.The only caution light directly con-nected to the external power section isthe EXT PWR caution light. Thislight will illuminate anytime the exter-nal power access door is open.

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Digital Automatic Stabilization Equipment SystemThe digital automatic stabilizationequipment (DASE) is provided to assist crewmembers in the control of the

aircraft. This system includes: the stability augmentation system (SAS), th e command augmentationsystem (CAS), the attitude hold, turn coordination, hover augmentation system(HAS), and the heading hold, andbackup control system (HUCS).Controls and indicators associatedwith the DASE are the automatic stabilization equipment (AS E) control

panel, cyclic sticks, crewstation C/Wpanels, squat relay switch and circuitbreakers.The DASE consists of the DASEcomputer, the ASE panel, two trans

formers, eight crewstation linearvariable differential transducers,four SAS transducers , eight shear pinactuated decouplers, eight HUCStransducers, and tracer wires.

The DASE interfaces with the visual display unit, the multiplex busand the air data sensor system(ADSS) for ground speed, side-slipand validity information. I t also interfaces with the heading and attitudereference set (HARS) for pitch, rollan d yaw rates, and for longitudinalvelocity, l ateral velocity and validityinformation.

The ASE panel (figure 5) containsthe switches necessary for controlling/testing of the numerous DASEfunctions, and is located on th epilot's left-hand console.

The PITCH, ROLL, YAW, ATTD/HOVER HOLD engagementswitches are two-position toggleswitches spring loaded to the 0 FF position. With electrical power from the28 Vdc bus No.2 applied to the DASEcomputer, and a valid built-in tester,movement of any of these switches tothe defined position will magneticallylatch the switch ON and engage thatfunction.

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The HUCS test switch is athree-position toggle switch springloaded to a center/off position.Holding the switch in th e pilot orCPO position will test the respectiveBUCS components a nd operation.There is one ASE release button located on each crewmember's cyclicstick (figure 6). Either button, whendepressed, will temporarily interruptpower to the magnetic latchingswitches in the ASE panel, causing allthe switches to drop to the OFF position.

The buttons are a means of emergency disengagement of the DASEfunctions, excluding HUCS.The trim feel release switch, previously described with flight controls,

permits attitude/heading synchronization when the DASE function is operable and either attitude retention orhover augmentation is in use.The HUCS select switch is aguarded trigger switch located on theunderside of th e CPO's collectiveswitch box. It provides the CPO witha means of taking control of the aircraft after control severance betweencrewstations or failure of a pilot' s linea r variable differential transformer transducer occurs.

Three caution/warning segmentlights advise the pilot of DASE operation. An amber BUC ON segment indicates one or more of the HUCS circuits are activated.

~ . " . ! e . t l i ' t 1 i % \ I i I ; " t ! ' i "ASE

BUCS TST YAWPlT ~ CPG Cf1

NOE/APRCH ROLL

Cf1 C?JATTD/HOVERHOLD PITCH

Cf1 Cf1FIGURE 5 Automatic stabilization equipment panel



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A red BUC FAIL segment indi-cates that one or more of the BUCScircuits have failed. An amber SAS segment indi-cates that one or more DASE compo-nents or functions have either failedor have been turned off.

The CPa's C/W panels containthe BUC ON, BUC FAIL and SASsegment lights.The squat switch disables yaw CASfunctions when the aircraft is on theground; however, this systemwill stillbe present in the pitch and roll axis. I fselected, the SAS functions will bepresent in all axes.Three circuit breakers (CBs) on thepilot's center CB panel control thepower for the operat ion of the DASEand the BUCS.The ac circuit supplies the requiredpower to the two transformers for lin-ear variable differential transformer

PILOT CYCLIC CONTROLS

FIGURE 6 . CycliC and collective controls.

JANUARY 1988

transducer operations.Direct current powers the DASEcomputer and the BUCS circuits .The SAS provides rate damping inthe pitch, roll and yaw axes. This is ac-complished by an electrohydraulicservo valve that is an integral part ofeach hydraulic actuator.The SAS signal is applied to theelectrohydraulic servo value thatdrives the SAS actuator. The SAScommand is also applied to a soft-ware model of the actuator (by theDASE computer), and is comparedto the SAS actuator position feed-back monitored by the SAS linearvariable differential transformertransducer. This feature provides themeans to verify the actuator responseto SAS command.When the actua tor position and themodeled signal differ by 35 percent orgreater, the computer will shut down

CPGs CYCLIC CONTROLS

the axis, disengage the SAS actuatorsolenoid and the respective ASEpanel engage switch, and trigger theSAS C/W light to advise the pilot ofan axis disengagement.Information used to produce SASactuator signals comes from the air-craft angular rates that are deter-mined by the HARS.DASE computer monitors the con-trol position established by thepilot/CPO and, based on the HARSreference, will adjust the actuator po-sition to maintain the aircraft at thedesired position.The command augmenta tion sys-tem is used to prevent the aircraftfrom being sluggish in response to thecontrol inputs required for maneu-vering, while not affecting the stabil-ity obtained from the SAS.The gain and shaping of the CASincreases the initial rate response in

CPGs COLLECTIVESWITCH BOX

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The AH-64A Apache, manufactured by McDonnell Douglas Helicopter Company.

the pitch, roll and yaw axes to providethe desired control harmony andquickness of response.Gain programing of the CAS withairspeed is used when less aircraft response per cyclic motion is desired athigher airspeeds.

The CAS signals are washed outwith time, based on control information. Information used to producecommand augmentat ion system signals comes from control positiontransducers (linear variable differential transformer/transducers).Yaw CAS functions are disabledby the squat switch while the aircraftis on the ground. More than 60 knotsindicated airspeed, with the yaw axisengaged, turn coordination is enabled. When enabled, yaw CAS is inhibited.

A limited authority attitude holdmode is provided in the pitch and rollaxis of flight. This will provide the pilot with limited hands-off flying capabilities in cruise or holding patternflight, allowing more time to concentrate on other duties.Attitude hold is functional whenthe ATTD/HOVER HOLD,

PITCH and ROLL switches on theASE panel are engaged, force trim is

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on, and the longitudinal airspeed ofthe aircraft is 60 knots true airspeed(TAS) or greater.The loss of any of the above functional requirements will cause attitude hold to disengage.A limited authority turn coordination function is provided through theyaw stability augmentation equipment using sideslip information fromthe ADSS. This function will be provided automatically above an airspeed of 60 knots TAS whenever theyaw SAS is engaged.

Turn coordination is inhibitedwhen the ADSS or HARS failure occurs. Yaw CAS is inhibited duringturn coordination.The hover augmentation system isdesigned to reduce pilot workloadduring hover and low speed flight byassisting the pilot in maintaining a desired position.The hover augmentation functionrequires that the ATTD/HOVERHOLD switch and PITCH, YAW orROLL switches on the ASE panel beengaged. This is provided for flightsbelow 50 knots T AS and 15 knotsground speed, and references lateraland longitudinal linear accelerationsignals received from the HARS.

Heading hold is provided to reducepilot workload in maintaining a desired heading below 50 knots T AS. Itwill be switched in automatically withthe HAS engagement.For heading hold engagement, theyaw SAS mustbeON. The command

augmentation function of the yawmode will go into synchronizationwhen the cyclic force trim releaseswitch is pressed or pedals are displaced more than 0.25 inches.The heading hold mode uses heading reference from the HARS, and nomore than 50 percent of the yaw SASactuator authority.

The BUCS functions within theDASE computer to provide fo rnonredundant, emergency, fly bywire, backup control operation of helateral, longitudinal, collective anddirectional servos if the primary mechanical control path is jammed orsevered.

Direct electrical control of theflight control system electrohydraulicactuators is accomplished by usingthe control position linear variabledifferential transformer/transducersfor generating actuator position command thro